Field of Invention
This invention relates to a method for curing a spin-on-glass (SOG) film formed on a multi-layered metal layer of a highly integrated semiconductor device, and more particularly, to a method for curing a SOG film by ultraviolet ray irradiation of the SOG film formed on a multi-layered metal layer of the semiconductor device.
When a multi-layered metal layer in the semiconductor device above 1 mega byte is manufactured, a SOG film is formed in order to flatten step differences and to insulate the metal layers from one another. However, since SOG film has a property such as a polymer and does not have as much insulating property as desired, SOG has to be cured through a curing process so as to improve the insulating property.
Accordingly, the curing process in the prior art is performed by infrared heat treatment in a furnace. This process is actually implemented in such a manner that a first heat treatment is performed in a hot plate for 1 minute at a temperature of 180 .degree. C. The second heat treatment is then performed in the furnace for 30 minutes at a temperature of 420.degree. C., thereby obtaining an improvement of the insulating property of the SOG film which is required for a highly integrated semiconductor device.
However, heat treatment of the SOG film in accordance with the prior art method results in the occurrence of cracks inside the SOG film, thereby deteriorating the insulating property. Also, as result of the heat treatment in the furnace, contamination occurs in the semiconductor device and damage occurs to other layers under SOG film.
Since a plurality or batch of wafers are placed in a processing apparatus, the entire batch wafers may be damaged if the apparatus has an operational failure.
Therefore, it is an object of the present invention to provide a method for curing the SOG film which can eliminate the formation of cracks which result in deterioration of the insulating property of the cured SOG film.
Specifically, it is an object of the present invention to provide a method for uniformly curing the SOG film in which the method comprises performing ultraviolet ray irradiation to the top of the SOG film simultaneously with performing indirect heat treatment to the SOG film by applying heat to the bottom of the wafer.
According to an aspect of the present invention, it is possible to protect SOG film against cracking by applying lower heat than that in the furnace in accordance with the prior art method, thereby improving the insulating property of SOG film.
According to the another aspect of the present invention, it is possible to cure the SOG film uniformly by the ultraviolet ray irradiation on the top of SOG film, thereby providing the preferred cured SOG film.